Selection against Neandertal deleterious alleles – “‘Approximately 2-4% of the human genome is in non-Africans comprised of DNA intro- gressed from Neanderthals. Recent studies have shown that there is a paucity of introgressed DNA around functional regions, presumably caused by selection after introgression. [U]sing previously published estimates of inbreeding in Neanderthals, and of the distribution of fitness effects from human protein coding genes, we show that the average Neanderthal would have had at least 40% lower fitness than the average human due to higher levels of inbreeding and an increased mutational load, regardless of the dominance coefficients of new mutations. Using simulations, we show that under the assumption of additive dominance effects, early Neanderthal/human hybrids would have experienced strong negative selection, though not so strong that it would prevent Neanderthal DNA from entering the human population.'” – @dienekes’…

…but see greg cochran: Degenerate Neanderthals – “Part of the problem is that the model is probably too simple. There is an argument, which makes sense to me, that suggest that small-N populations do better than you would think, because as the average population fitness gets farther from the optimum, strongly beneficial compensatory mutations become more and more possible.”

A Few Months of Evolutionary Change Reshapes a Whole Community – “The overall lesson is that evolutionary change is constant, and that evolving populations can change the very environments to which they’re adapting. Natural selection isn’t shaping species to achieve some single ideal version of themselves, but in pursuit of constantly moving targets — and that’s worth keeping in mind no matter we’re talking about Daphnia magna or Homo sapiens.”

Size (Population) Matters for Inbreeding – “Presumably, in large populations there will be many low frequency variants of weak deleterious effect and recessive expression. In contrast, in small populations the power of drift is such that even rather deleterious alleles can be fixed against the gradient of selection. At cross-purposes with this is the idea that because inbreeding populations tend to ‘expose’ alleles which express recessively to selection they can ‘purge’ the genetic load which drags on fitness…. What [the researchers] found is that in line with theoretical prediction those sampled from large populations had lots of segregating deleterious alleles, which manifested in strong inbreeding effect when individuals were purposely crossed with those genetically similar. In contrast, those from small populations did not exhibit so much inbreeding effect, indicating that a lot of the deleterious alleles were already fixed and so exposed. These individuals from small populations also exhibited lower fitness than those from large populations, reflecting in all likelihood their genetic load. Crossing individuals from different small populations resulted in immediately hybrid vigor, as the fixed variants differed across lineages.” – from razib.

Fires in the Forest: The Revolution in Human Evolution – “On top of the story of migrations of whole peoples, and the extinction and absorption of others, is the story of bands of men operating as units, related either in truth or fictively, which extract rents across a thickly populated landscape of human cattle.” – also from razib.

Regression to the Mean – “Clever people might notice that all of HBD is based on just two concepts: behavioral genetics (or again, more broadly, heritability) and the breeder’s equation. Know those two things and most of the rest follows.” – from jayman.

The Correlation Between g Loadings and Heritability in Russia – “Data from 402 twins aged 13 and 296 twins aged 16 showed correlations of r=−0.45 and r=−0.60, respectively. It is concluded that the two data points are clearly not in line with established findings. It may be that the link between g loadings and heritabilities is more complex than previously thought.” – h/t sketchy person!

Are CEOs Born Leaders? Lessons from Traits of a Million Individuals – “CEOs have higher cognitive and non-cognitive ability scores and are taller than typical members of the population. The difference in traits is larger when CEOs run bigger companies; it is smaller when they run family firms, in particular in the capacity of an heir or in a less competitive industry.” – h/t ben southwood! who tweeted: “CEOs: in the top 5% of smarts, height and well-adjusted personality at age 18”

The Quantitative Genetics of Disgust Sensitivity – “Twin modeling revealed that approximately half of the variation in pathogen, sexual, and moral disgust is due to genetic effects. An independent pathways twin model also revealed that sexual and pathogen disgust sensitivity were influenced by unique sources of genetic variation, while also being significantly affected by a general genetic factor underlying all 3 disgust domains. Moral disgust sensitivity, in contrast, did not exhibit domain-specific genetic variation.” – h/t erwin schmidt!

Inter-group conflict and cooperation: field experiments before, during and after sectarian riots in Northern Ireland – “The idea that cooperative groups out-compete less cooperative groups has been proposed as a theoretical possibility for the evolution of cooperation through cultural group selection…. In this study we test the hypothesis that inter-group conflict promotes parochial altruism (i.e. in-group altruism and out-group hostility) by using longitudinal data of a real-world measure of cooperation – charity and school donations – sampled before, during and after violent sectarian riots between Catholics and Protestants in Belfast, Northern Ireland. We find that conflict is associated with reductions in all types of cooperation, with reduced donations to a neutral charity, and both in-group and out-group primary schools. After the conflict, both in-group and out-group donations increased again. In this context we find no evidence that inter-group conflict promotes parochial altruism.”

Interactions between personality and institutions in cooperative behaviour in humans – “We investigate interactions between personality and a punishment situation via two versions of a public goods game. We find that, even in a strong situation, personality matters and, moreover, it is related to strategic shifts in cooperation. Extraversion is associated with a shift from free-riding to cooperation in the presence of punishment, agreeableness is associated with initially higher contributions regardless of game, and, contrary to our predictions, neuroticism is associated with lower contributions regardless of game. Results should lead to new hypotheses that relate variation in biological functioning to individual differences in cooperative behaviour and that consider three-way interactions among personality, institutional context and sociocultural background.” – h/t andrew sabisky!

Nonreligious children are more generous – “Religious doctrines typically urge the faithful to treat others with compassion and to put the greater good before selfish interests. But when it comes to generosity, nonreligious kids seem to be more giving, according to a new study of 1170 children from around the world. Children from religious homes — particularly Muslims — also showed a greater inclination to judge someone’s misdeeds as wrong and punish the perpetrators…. Muslim children on average gave the highest rankings and sought harsher punishments than either their Christian or secular counterparts. Decety says he is unsure why this is the case.” – h/t jayman! see also staffan who tweeted: “Religious or not often coincide with Clannish and WEIRDO. A big and likely confound overlooked.” and me: “would’ve been nice if they’d broken down the race/ethnicities for the u.s., canadian, and south african samples.”

Sex and STEM Occupation Predict Autism-Spectrum Quotient (AQ) Scores in Half a Million People – “As predicted, sex and occupation differences were observed: on average, males (m = 21.55, SD = 8.82) scored higher than females (m = 18.95; SD = 8.52), and individuals working in a STEM career (m = 21.92, SD = 8.92) scored higher than individuals non-STEM careers (m = 18.92, SD = 8.48). Also as predicted, age and geographic region were not meaningfully correlated with AQ. These results support previous findings relating to sex and STEM careers in the largest set of individuals for which AQ scores have been reported and suggest the AQ is a useful self-report measure of autistic traits.”

Seven Dimensions Of Personality Pathology Are Under Sexual Selection In Modern Spain – “In a sample of 959 outpatients, we examine whether, and how, sexual selection acts on seven main dimensions of personality pathology, taking into account mating success, reproductive success, and the mediating role of status. We find that, to varying extents, all personality dimensions are under sexual selection. Far from being predominantly purifying, selective forces push traits in diverging, often pathological, directions. These pressures differ moderately between the sexes. Sexual selection largely acts in males through the acquisition of wealth, and through the duration (rather than the number) of mates. This gives a reproductive advantage to males high in Persistence-Compulsivity. Conversely, because of the decoupling between the number of mates and offspring, the promiscuous strategy of psychopaths is not so successful. Negative Emotionality, the most clinically detrimental trait, is slightly deleterious in males but is positively selected in females, which can help to preserve variation…. An evolutionary perspective on PDs can provide a better understanding of their nature and causes than we have achieved to date by considering them as illnesses.” – h/t siberian fox!

No evidence that polygynous marriage is a harmful cultural practice in northern Tanzania – “We present counterevidence that polygyny is often positively associated with food security and child health within communities and that, although polygyny and health are negatively associated at the group level, such differences are accounted for by alternative socioecological factors. These results support models of polygyny based on female choice and suggest that, in some contexts, prohibiting polygyny could be costly for women and children by restricting marital options.” – h/t sergey gavrilets!

The missing hour of sleep – “In reality, there is no single human nature. Genetic evolution didn’t slow down when humans began to split up and settle the different continents. It accelerated. And not just because our ancestors were adapting to different natural environments. Most of the acceleration took place long after the globe had been settled from the equator to the arctic. It happened when humans began to adapt to an increasingly diverse range of cultural environments. And those adaptations were mostly behavioral and psychological. One of them is the way we sleep. The African sleep pattern is normal in its native environment. It is simply an adaptation to a particular set of circumstances, just as the northern European sleep pattern is an adaptation to another set of circumstances.” – also from peter frost.

Changes in Inequality and Generalized Trust in Europe – “This paper analyses the determinants of trust in a pool of 34 European countries over the period 2002–2012. We find that income inequality is negatively related with generalized trust when we analyze the pooled data of individuals with multilevel models, confirming a well-established result in the analysis of cross-country differences in trust…. In contrast, in the fixed effects models, we find negative and significant effects of ethnic and linguistic fractionalization, discrimination (general or based on migrant status) and crime rates on trust.” – behind a paywall.

i’ve been trying to think through polygamy and if there’s any potential there for the selection for clannishness like i think there is with long-term cousin marriage. (i think i might have sprained a parietal lobe while doing so. (*^_^*) ) i very much have subsaharan african societies in mind here, but, of course, polygamy occurs elsewhere, too.

on the surface it seems obvious that long-term polygamy ought to set the stage for the possible selection for clannish behaviors like cousin marriage (imho) does. like repeated cousin marriage, strict polygamy ought to narrow the relatedness within a population — the result of strict polygamy should be a greater number of half-siblings in a population than in a randomly-mating population, and, of course, half-siblings are more closely related to one another than non-siblings, so a society full of half-siblings could potentially lead to an accelerated selection for nepotistic altruism in a way similar to cousin marrying societies.

however, one big difference is that in polygamous societies generally — even in subsaharan african societies (where there’s a lot of polygamy) — people do not marry/mate with their half-siblings. (it does occasionally happen in some subsaharan societies, but only occasionally.) so, unlike in cousin-marriage societies, “genes for nepostistic altruism” (whatever they might be) might *not* become concentrated in family lineages. yes, there are a lot of half-siblings in polygamous societies, but any particular nepostistic altruism (“clannishness”) genes they might have (gotten from their fathers) will get diluted as they move out into the general population and marry non-relatives. if polygamy isn’t a driver of accelerated selection for nepotistic altruism (and i’ve rather persuaded myself that it isn’t), that could explain why subsaharan africans are generally pretty civic-minded, comparatively speaking. (the poor outcomes seen in african nations are perhaps more the result of other factors like low iq, high disease rates, etc., rather than clannishness. dunno. Further Research is RequiredTM.)

i should note here that polygamy in subsaharan africa is extremely variegated — in some societies, it’s typical for the first wife to actually be a cousin, and then the rest not. so there can be a layer of cousin marriage in amongst the polygamy. in other societies, cousin marriage is completely avoided. in yet other societies, the series of wives might be sisters (sororal polygyny), which makes all the offspring not only half-siblings (because they have the same father) but also cousins (because their mothers are sisters). here you would think that any selection for nepotistic altruism should very much be amplified. of course, in many subsaharan african societies — especially the polygamous ones — there’s often a lot of hanky-panky going on, so not all of the siblings will truly be half-siblings, etc. that’ll dilute your genes for nepotistic altruism right there.

another thing i also thought of regarding subsaharan and/or polygamous societies is the fact that all of the half-siblings don’t always grow up together. in patrifocal polygamous societies, yes — there you’ll have one man living with all of his wives (poor fellow!) and all of his kids, so all the half-siblings will be raised in the same place and interact with one another — and, presumably, continue to do so as adults. in matrifocal societies, a mother and her children reside with the mother’s family, not her husband and his family. this occurs in some polygamous societies, too.

it seems to me that, even if polygamy was a driver of accelerated selection for nepotistic altruism, such selection couldn’t possibly happen if the carriers of the clannishness genes don’t interact. if the half-siblings from polygamous unions don’t grow up together, or don’t interact much as adults, but rather with their (ordinary, i.e. not inbred) cousins, how would clannishness be selected for? it wouldn’t, i don’t think. or it wouldn’t be selected for in an amplified, accelerated way (which is what i think happens in the long-term cousin marriage scenario).

and that’s as far as i got with thinking through polygamy (i shall return to this topic, i’m sure). but thinking about the patrifocal vs. matrifocal family types got me to thinking about something else.

thought experiment: let’s say you eliminate cousin marriage from a population, but don’t eliminate the extended family. say you get rid of the inbreeding, but individuals continue to interact mostly with their close (extended) family members — more so than with the other members of society who are unrelated to them. you would think that it would take longer for clannishness to disappear — for “genes for nepostistic altruism” to get diluted in the population — than in a society where both cousin marriage AND the extended family were simultaneously eliminated.

i am, of course, talking about medieval western versus eastern europe here. the extended family was eliminated quite early in the middle ages in western europe via manorialism along with cousin marriage (serious changes to both were well underway in western europe by the 800s). in eastern europe, the cousin marriage bans appeared later simply because christianity had arrived later. and, especially the further east one goes (like into russia), the fewer pressures there were to eliminate the extended family. quite the opposite, really. for example, this was the situation in the baltic regions, including belorussia, in ca. the fifteenth century [pg. 440]:

a “…’kinship holding’, was collectively held by the extended family. Rural settlements often contained more than one kinship holding, and each holding was in turn subdivided among smaller households within the extended family….”

and in russia as late as the late seventeenth and early eighteenth centuries [pg. 444]:

“Russian manorialism was distinctive in several important ways…. In Russia…it was the peasant commune that allocated these taxes and obligations among the households. The village commune in Russia had emerged in the late seventeenth or early eighteenth centuries in response to increasing demands from the state and the landowning elite; peasant communes not only allocated obligations, but also chose their officials, held court, selected recruits for conscription levies, and kept written records of their activities. The communal clerk was sometimes the only member of his commune who could read and write….

“[O]n Russian manors, where hired labour was often not available, the peasant family had to personally perform labour obligations at the same time that it worked its own farm. This required large, often multi-generational, households with enough labour capacity to serve the simultaneous needs of both the manorial economy and the family farm…. As Steven Hoch has shown, however, life in the large household was hardly a rural idyll; household patriarchs formed a communal elite that ruled with despotic brutality, ruthlessly exploiting their families and denying any autonomy to the adults under them. At the same time, however, the large household also protected the peasant family from ruin.”

even if eastern europeans/russians began to avoid cousin marriage around, say, 1000 (conversion to christianity), they didn’t quit residing in extended families and mostly interacting with their extended family members until, like, yesterday. (again, this pattern appears to be more pronounced the further east one travels.) so the dilution of nepotistic altruism genes in eastern european populations — via nepotistic behaviors being misapplied to individuals not sharing the same altruism genes (i.e. unrelated individuals) — didn’t happen as quickly as it did in western europe where people began regularly interacting with non-kin much earlier in the middle ages.

A Surprise for Evolution in Giant Tree of Life – “Researchers build the world’s largest evolutionary tree and conclude that species arise because of chance mutations — not natural selection…. This controversial proposal stems from efforts by Hedges and collaborators to build the world’s most comprehensive tree of life — a chart plotting the connections among 50,000 species of Earth’s vast menagerie. Their analysis suggests that speciation is essentially random. No matter what the life form — plant or animal, insect or mammal — it takes about 2 million years for a new species to form. Random genetic events, not natural selection, play the main role in speciation.” – see also Was Charles Darwin Wrong About Speciation? from razib.

Behavioral idiosyncrasy reveals genetic control of phenotypic variability [pdf] – “If we could rear genetically identical individuals from a variety of genetic backgrounds and rear them in the same environment, how much phenotypic variation between individuals of the same genotype would we see? Would different genetic backgrounds differ in their degree of variability? What would account for these differences? We used Drosophila inbred lines to address these questions focusing on variability in locomotor handedness. We show that different genotypes vary dramatically in their propensity for variability, that phenotypic variability itself, as a trait, can be heritable, and that loci affecting variability can be mapped. The genetic control of variability has received little attention in quantitative genetics despite the important role variability plays in explaining phenotypic variation between individuals.”

Ancient DNA Tells a New Human Story – “The study of ancient DNA has challenged this view. We now know that mass migrations occurred repeatedly, overwhelming natives while absorbing some of their genes…. Joseph Pickrell of Columbia University and David Reich of Harvard University argue that ‘major upheavals’ of human population have been ‘overwriting’ the genetic history of the past 50,000 years. The result, they say, is that ‘present-day inhabitants of many places in the world are rarely related in a simple manner to the more ancient peoples of the same region.'” – from matt ridley.

Three hundred years of low non-paternity in a human population – “Here we use this approach to investigate 1273 conceptions over a period of 330 years in 23 families of the Afrikaner population in South Africa. We use haplotype frequency and diversity and coalescent simulations to show that the male population did not undergo a severe bottleneck and that paternity exclusion rates are high for this population. The rate of cuckoldry in this Western population was 0.9% (95% confidence interval 0.4–1.5%), and we argue that given the current data on historical populations we have to conclude that, at least for Western human populations, cuckoldry rate is probably in the range of 1%.” – h/t debbie kennett!

whenever i’m kinda tired and slightly braindead, i usually start trawling the streets google books or online journals for any info/data on mating patterns in human populations. (unless i rewatch star wars for the umpteenth millionth time, obviously.) it’s my own, personal form of trainspotting just with less trains. and more mating patterns.

so i thought i’d share with you what i’ve got to date for sub-saharan (ss) african populations. this is faaar from being a complete list, nor is it systematic in any way. it’s just the stuff that i’ve happened to come across so far, so don’t read anything into the list like “overall there seems to be more inbreeding or outbreeding” or whatever.

first of all, there are a LOT of ss african populations! thousands. so, you know, it’ll take some time to get info on them all! here’s a map of the broad ethnolinguistic groups of africa that i’ve stolen from wikipedia — remember that there are hundreds if not thousands of subgroups within these broad groups:

needless to say, with such a wide variety of peoples, there is also a wide variety of mating patterns in ss africa. some populations avoid cousin marriage altogether. we’ve already seen this with the bamileke of cameroon and the igbo of nigeria. also the turkana of kenya and quite possibly the amhara of ethiopia (not 100% sure about them — need to double-check). a notable group which apparently avoids cousin marriage is the zulu. but plenty of other ss africa groups do practice cousin marriage like, as you’ll see in the table below, the kongo and luba in the democratic republic of congo, the ashanti in ghana, the sotho-tswana in south africa, and the kpelle of liberia. (fun fact that’s stuck in my brain for some reason — some of oprah’s ancestors were probably kpelle.)

the most common form of cousin marriage in ss africa is mother’s brother’s daughter (mbd) marriage which isn’t too surprising since that is the most common form of cousin marriage in the world. there’s an interesting twist to it in ss africa, though, thanks to all of the polygamy which is also very common in ss african societies. here from robin fox [pg. 195]:

“This latter form of marriage [mother’s brother’s daughter] is common in Africa and in patrilineal societies generally. Often, in Africa, it goes along with marriage to the wife’s brother’s daughter, as shown in diagram 4.2. A man either marries his wife’s brother’s daughter or passes the privilege on to his son (at least this is one way of looking at it). In many societies it is simply a straightforward privilege to marry the mother’s brother’s daughter.”

so, yeah, in case you were wondering, that would make the kids of these two wives (wife number one/aunt and wife number two/niece) both half-siblings and first cousins once-removed. and the children of wife number one are the first cousins once-removed to their father (and mother). and the children of wife number two are second cousins to their father. i think. i’ll let you think about it for a while. (~_^)

there is some father’s brother’s daughter (fbd) marriage (the type favored by the arabs) in some areas of ss africa — most notably amongst the hausa and fulani in northern nigeria, and the songhai and soninke in mali — but these are all muslim groups who i would guess picked up fbd marriage from the arabs/north african groups that introduced islam to them. youssef courbage and emmanuel todd think otherwise [pg. 43]:

“So-called Arab marriage, accepting union with any first cousin, but preferably with the father’s brother’s daughter, is not characteristic of sub-Saharan Africa. It is widely practiced only by the Fulani, nomadic herders of the northern fringe, immediately south of the desert, at a level so much higher than the Arab norm that it probably had an independent origin. It is also characteristic of some sedentary groups in the same area (Soninke in Senegal, Mali, and Mauritania; Songhai in Mali; Hausa in northern Nigeria). In West Africa, marriage is usually either exogamous or characterized by a preference for cross-cousin marriage, that is, between the children of a brother and a sister, a practice that has nothing to do with Islam.”

i don’t know if that statement about the fulani practicing a greater amount of fbd marriage than the arabs is correct or not. i shall have to try and find out. (here might be a good place to start.) i think it’s more likely that, being that the fulani have obviously been in contact with the arab/muslim world for quite a long time, they picked up the practice in that way. the afghanis and pakistanis also practice quite a lot of fbd marriage even though they’re at the edge of the “arabized” world, albeit at the other end of it, so i doubt that distance from arabia matters much here. it’s the contact with the greater arab world that counts.

two ss african groups that do seem to have adopted fbd marriage independently are the sotho-tswana and venda of south africa. need to learn more about those two groups. (note that the fbd marriage recorded in the table for the tutsi in rwanda refers only to some of the elites, not the general population.)

additionally, as in christian europe (especially medieval europe), some ss african groups prohibit marriage between in-laws — which is interesting. one example are the yao of malawi. they, however, happen to have a preference for cross-cousin marriage.

again, the other mating practice that is very common in ss africa is polygamy. i’ve said a few times here on the blog that you’d think that that would narrow the gene pool/relatedness between individuals in a group just as cousin marriage does. it might not always, though, because polygamy is not one thing either (can nothing ever be easy and straightforward?! (~_^) ). the lozi of zambia, for instance, apparently practice (or did traditionally) a sort of rapid serial polygamy, with wives being shuffled rather quickly on to the next husband, so that wouldn’t really narrow the genetic relatedness in the population at all, afaics. quite the opposite really. on the other hand, some groups practice sororal polygamy with the men making sure to marry sets of sisters, so that would narrow the relatedness in the group more so than a more basic form of polygamy in which men married women more randomly. the conclusion wrt polygamy, i think, is that each group will have to be evaluated on an individual basis. (*sigh*)

problem number one: for my purposes, since i’m interested in evolution and the selection of behavioral traits, i need to know how long populations have been inbreeding or outbreeding for, since natural selection does take some amount of time (but not necessarily millions of years). that’s difficult to work out for ss africans (and most of the world for that matter) without historic records or reams of genetic data which we haven’t got yet. it might be possible to reconstruct some of the history of mating patterns for some of the groups in ss africa from colonial accounts, especially those of missionaries who also acted as early ethnographers in many ways. we shall see. it would certainly be interesting to know for how long some of these groups have been inbreeding or outbreeding. as we’ve already seen, for instance, wikipedia claims that the igbo had a “quasi-republican” form of government in the 1400s with some sort of one-man-one-vote system. that’s not a system you find in heavily inbreeding societies — at least none that i can think of. what if it’s connected to the igbo outbreeding? dunno. Further Research is RequiredTM — and most likely it’ll have to be genetic.

problem number two: don’t have a whole lot of info on the rates of cousin marriage (or not) for most of these populations either. that’s also an extremely important detail to know. here are the few groups that i do have some numbers for:

– the fulani of burkina-faso: 65.8% first and second cousin marriage rate– the fulani, mandinka, and wolof in gambia: 65% of first marriages of men are to a cousin – that’s an average of the three populations, and i don’t have a breakdown for each group– the fouta-jallon (taramabli-dionfo) of guinea: 25.9% cousin marriage rate– the yoruba of oka akoko in nigeria: 51.2% cousin marriage rate– the lobedu (sotho) of south africa: 30% cousin marriage rate

so, there’s a variety in the rates, too. again, not surprising.

i think that’s it by way of the intro, so without further ado, here is my table. oh, the populations highlighted in yellow are those which include more than ten million people. and many of these groups spill over into other countries, of course, apart from the ones in which i’ve listed them [click on table for LARGER view – should open in new tab/window]:

been meaning to do a follow up post on the bamileke of cameroon since … well, since last november! always on top of things here at the hbd chick blog. (*^_^*) so, at long last, here we go….

oh. in case you don’t recall or didn’t realize, i’ve been trying to track down other outbreeders around the world — populations which have avoided close relative marriage (closer than second cousins) over the long term (say 30 or 40+ generations) — to see what they’re like: what their family structures are like, what their social structures are like, if they’re corrupt or nepotistic or have a lot of infighting between families/clans, etc. i’m interested in finding out if there are any general behavioral traits common to outbreeders. same for the inbreeders, too, actually.

the bamileke are outbreeders. they avoid all marriage with anybody on their mother’s side of the family (their matrilineage), and also tend to avoid marriage to third cousins or closer on the father’s side [pg. 149]:

“The matrilineage is comprised of all the people descended through women from a common female ancestor. Since all female descendants of the matrilineage are considered his sisters, a man must not marry within this group. No specific taboos exist against marriage within a patrilineage, although most Bamileke who share a common male ancestor four generations back [i.e. a great-great-grandfather-h.chick] will not intermarry. Whereas members of a patrilineage live close to each other and regularly commune with each other, those of a matrilineage are not close and may, in fact, belong to different chiefdoms.”

the bamileke, however, like many african groups, practice polygamy which probably narrows the genetic relatedness in the population. i don’t have any figures on how much polygamy is practiced there.

don’t know for how long the bamileke have been avoiding close cousin marriage, but i suspect that it is at least a few hundred years. the bamileke first came up here on the blog in a previous post, flatlanders vs. mountaineers revisited, in which we saw that they are some of the cameroon highlanders many of them living in very mountainous regions of cameroon, but yet their mating patterns — i.e. avoiding close cousin marriage — don’t seem to fit the broad pattern of highlanders or mountain folk typically inbreeding. apparently, however, the bamileke are fairly recent arrivals in the highlands, having migrated from the (flat) adamawa plateau somewhere around the 1600s [pg. 261 – links added by me]:

“As for the Bamileke, their ancient history is closely linked to that of the two previous groups. All came from the north, from the region today occupied by the Tikar. Their migration probably began in the seventeenth century and took place in successive waves.”

so, it could be that the bamileke are long-term outbreeders (because they originally came from a flatlander region) who transplanted themselves into more mountainous regions beginning ca. four hundred years ago. they don’t seem to have adopted a mountaineer economy — pastoralism for instance — but, rather, stuck to farming. what might have (ironically) saved them from eventually having to adopt pastoralism was the arrival of the germans who introduced coffee growing to the cameroon highlands. the bamileke quickly adopted the cash-crop system of coffee growing and trading with europeans. not sure about this, though — just a guess on my part.

it might be impossible to reconstruct the history of the bamileke people’s mating patterns from historical records (which will have been written almost solely by europeans, of course). if i find any published accounts by christian missionaries in cameroon, they might include some info on the bamileke. otherwise, genetic data (runs of homozygosity) would probably be the best way to discover how in- or outbred the bamileke are. for now, all i can say is that currently (in the twentieth and twenty-first centuries) the bamileke are outbreeders. and judging by their history, there’s a good chance that they’ve been outbreeders for a few hundred years, but that is just speculation on my part.

having said that, what are the bamileke like? what are their family types and social structures like?

one subgroup of the bamileke, the bangwa (bangoua – in french), are described thusly [pg. 1]:

“Nor is Bangwa a ‘lineage-based’ society. Bangwa social life is not carried on in the all-embracing idiom of kinship, with personal loyalties and resources pooled in discrete unilineal descent groups. Kinship here is an individual business, with a person in the centre of a ramifying network of ties linking him with matrilineal and patrilineal kin, affines, creditor-lords, political superiors and so on. A Bangwa claims no clan or lineage membership, and no corporate group takes responsibility for any of his actions. Kinship is an aid to the business of making a living: tradiing, inheriting, acquiring a title, farming, ruling and marrying. And as the business of living is complex in Bangwa so is the kinship system.”

these features — not having tight clans or even lineages, individuals having to take responsibility for their own actions — are very much like what we see in the long-term outbreeding european populations. don’t know if the rest of the bamileke are like the bangwa in these regards, but i’m guessing yes, since i haven’t read any descriptions anywhere of bamileke peoples engaging in blood feuds or having a wergeld-like system. this absence of tight clans/kindreds seems outbred to me.

“Customary political structures revolve around kinship, which the Bamileke define by dual descent — patrilineal ties typically determine village residence and rights to land, but matrilineal ties define ritual obligations and the inheritance of movable property.”

so larger kinship groupings are not totally unimportant to the bamileke.

“Although the group solidarity of the Bamileke is strong, individual achievement is highly valued. Members of the group are expected to exercise individual initiative in the pursuit of economic goals. Individual acquisition of economic resources including private property, money, and other remuneration is stressed. Other cultural characteristics of the group that have been invaluable to their entrepreneurial skills are discussed below….

“[T]he social status of an individual in this ethnic group is not rigidly fixed; individuals — male or female — can improve their condition in life and are expected to do so. Commercial and business success is one of the most highly valued routes to prestige and status. Bamileke women are also expected to achieve economic and comnercial success and there are few traditional limits placed on their economic participation….

“The traditional values of the Bamileke stress individual competition and overt displays of ‘getting ahead’. Individual Bamileke are expected to compete and to surpass each other’s accomplishments. The emphasis on competition is not limited to economic activities, but is a feature of personal relationships as well: within families, children are expected to compete with their siblings; sons and daughters are encouraged to surpass the achievements of their parents….

“[P]oorer relatives are not expected or allowed to lay claim to or live off the riches of wealthier family members….

“A final feature of traditional society which must be noted is the system of succession and inheritance. Of all the elements characteristic of Bamileke social organization, this feature has been fundamental and has had far-reaching implications for the rate and pace of Bamileke participation in economic growth, development, and change. Succession and inheritance rules are determined by the principle of patrilineal descent. According to custom, the eldest son is the probable heir, but a father may choose any one of his sons to succeed him. An heir takes his dead father’s name and inherits any titles held by the latter, including the right to membership in any societies to which he belonged…. The rights in land held by the deceased were conferred upon the heir subject to the approval of the chief, and, in the event of financial inheritance, the heir was not obliged to share this with other family members. The ramifications of this are significant. First, dispossessed family members were not automatically entitled to live off the wealth of the heir. Siblings who did not share in the inheritance were, therefore, strongly encouraged to make it on their own through individual initiative and by assuming responsibility for earning their livelihood….

“A notable feature of the group is the complementarity between individualism and collective unity. Individuals are expected to make their own way in the world while retaining a strong ethnic identity and group association. This interact is one of the factors accounting for their economic success. Each individual, for example, is expected to contribute as much to the group as he receives in return. Thus, cooperation is essential. The group is perceived of as an interdependent system based on the strength of individual links….

“A principal Bamileke belief is that individuals are, in the final analysis, responsible for their own fate. One makes one’s way in society on the basis of individual qualities. Status distinctions and rank are not rigidly fixed and there is always the possibility of advancement.”

so here we have: individualism, extended family NOT being able to automatically rely on other members of the extended family, no precise inheritance rules (which is something emmanuel todd identifies as a trait of absolute nuclear family societies), and the collective unity of the larger group (NOT any family group). these are all traits that are found in outbred, “core” europe — although they are expressed somewhat differently in northwest europe vs. cameroon.

“The original function of these societies was to administer initiation rites, but in societies with a more complex economy and polity, both male and female associations grew in importance by assuming a plurality of administrative and commercial functions as well, such as tax collection, price control in markets, maintenance of public order, and organization of collective work. The *mandjon* societies of Bamileke men and women provide good examples of such traditional associations. The women’s *mandjon* are presided over by the mother of the *fon* or chief — there are over a hundred such chiefdoms in Bamileke territory — and its members help each other in agricultural work. The *mandjon* used to meet on a weekly basis to organize such work. In addition to associations that fit into the political structure of Bamileke society, there are also many autonomous associations based on neighborhood. Aside from ritual functions (such as divination and faith healing) they also act as savings groups and associations for mutual assistance. More recently, Bamileke associations…have been adapted to the needs of urban living and have led to a proliferation of voluntary membership clubs that provide mutual aid, companionship for immigrants, and entertainment. The savings groups are maintained by members paying in fixed amounts at weekly meetings, taking turns in receiving the entire sum. Membership is not restricted to a single saving association and the Bamileke tend to join them as soon as they earn money.”

interestingly, the bamileke are probably the most successful group in cameroon economically speaking — and they are also strongly nationalistic [pg. 65]:

“In the towns and cities, they are known for their skills at running small and large businesses and for their professional abilities…. During the years of the French colonial empire, the Bamileke were leaders in the nationalistic rebellion, especially the 1955 uprising that led to Cameroon’s independence. Today the Bamileke are extremely influential in the Cameroonian commercial economy. They are also one of the major constituencies of the Union de Populations du Cameroun (UPC), the fiercly nationalistic political party.”

i haven’t found out anything yet on corruption in bamileke society — although there seems to be plenty of it in cameroon. can’t imagine that they’re very nepotistic since the members of extended families are not obliged to help one another out — nor is aid to be expected — but you never know. i will endeavor to find out more!

Y-chromosome “Adam” was not necessarily human – “From the point of view of population genetics, there is absolutely no reason that the common ancestor of all human Y chromosomes must have existed in an individual that we would identify as ‘human’.”

Genomic variation in sharing between siblings – “Visscher et al make really nice use of this slight variability in how much of the genome sibs share to learn about how much variation in height within a population is due to genetic variation. They use the fact that sibs who share slightly more of their genome (>0.5) should have more similar heights, than sibs who share less of their genomes (<0.5). This allows them to partition out how much of the resemblance between siblings is due to a shared environment, as opposed to shared genomes…. It also makes me wonder if sibs are actually unconsciously, weakly aware of these subtle genomic differences (through their similarity in a range of traits, including height etc). I could imagine doing a study where siblings (or others) are asked to assess how similar they are/feel, and then assessing whether this is weakly correlated with the fraction of the genome shared. I keep meaning to followup on this idea with some popgen theory to assess how this might play out in modifying kin-selection and altruism between sibs and other relatives." – from graham coop [this guy].

Why the masculine face? Genetic evidence reveals drawbacks of hyper-masculine features – “[A]round half the variation in both male and female facial masculinity could be attributed to additive genetic variation…. The extensive genetic variation in masculinity makes more plausible the idea that choosing to mate with a masculine man can result in more attractive offspring. But the genes that made a male face more masculine did not make it more attractive. Worse, these same genes made female faces more masculine and thus less attractive. Families that make manly-looking sons tend also to make masculine-looking daughters.”

Casting Out The Devil – “[C]onservatives generally think that liberals are misguided, and live in deep denial of obvious truths about human nature and the way the world actually works (as opposed to the way they think it *ought* to work), liberals view conservatives not just as misguided, but as *morally evil*.” – from malcolm pollack.

Bones from human sacrifice at Tenochtitlan ceremonial complex – “Fragments of human bones that exhibit cut marks and prolonged exposure to fire have been discovered through various excavations in the Sacred Precinct of Tenochtitlan (located in Mexico City). These skeletal remains are from individuals, such as children, slaves and captured warriors, who were sacrificed during religious festivals. – cannibalism! – h/t charles mann!

Life as a Nonviolent Psychopath – “Neuroscientist James Fallon discovered through his work that he has the brain of a psychopath, and subsequently learned a lot about the role of genes in personality and how his brain affects his life.” – this guy again. h/t ray sawhill!

still on vacation** (i know – it’s disgusting! (~_^) ) — but still reading! a bit.

i picked up this book (pub. 1969) in a used book store the other day (yes, an ACTUAL book store!). it includes a nice, although possbily out-of-date, summary of mating patterns/cousin marriage in native north american societies [pgs. 227-229 – links added by me]:

“COUSIN MARRIAGE

“First-cousin marriage was permitted or perferred by a small minority of peoples….

“On the northern Northwest Coast, cross-cousin marriage was the preferred kind of union. If no first cross-cousin was available to a man, he chose a more remote cousin designated by the same word in the language. Among the Haida, a boy of ten years of age ideally went to live with his mother’s brother, who gave him his education in the lore of the sib as well as in practical matters. When the boy reached marriageable age, he ideally married his mother’s brother’s daughter and continued to live in the house of his mother’s brother. When the latter died, the boy, who was now the deceased’s son-in-law and also his sister’s son, inherited his house, land, and chattels as well as his social position and prestige. If no mother’s brother’s daughter was available to a young man, he might substitute a father’s sister’s daughter, who was designated by the same kinship term in the language….

“Among the Kaska, inland from the Northwest Coast, the only first cousin a man was permitted to marry was his mother’s brother’s daughter. This was the preferred marriage, although many men had to be content with cousins further removed or with unrelated wives. At Lake Teslin, between the Kaska and the coast, and among the Chipewyans farther east, a man could marry only his father’s sister’s daughter.

“Proceeding farther east to the Cree and Ojibwa, we find a different picture. Although marriages with both kinds of first cross-cousins were permitted, they were less frequent than those with more remote cousins. Double cross-cousin marriage sometimes occurred; a man married a woman who was both his mother’s brother’s daughter and his father’s sister’s daughter at the same time. This could happen only when two men in the older generation had exchanged their sisters, each marrying the other’s sister. The offspring from these unions would be double cross-cousins. Figures on the frequency of single cross-cousin marriage show that the mother’s brother’s daughter was married more often then the father’s sister’s daughter. The pattern of the Montagnais-Naskapi of the Labrador Peninsula was similar to that of the Cree and Ojibwa.

“In California and Oregon, cross-cousin marriage was permitted or perferred only by a small minority of tribelets, and in every case the mother’s brother’s daughter was singled out. In the Great Basin, cross-cousin marriage was permitted in a minority of localities but was nowhere the preferred form. In the Southwest, only the Walapai permitted a man to marry either variety of cross-cousin. The Maya of the Yucatan appear to have had both kinds of cross-cousin marriage at the time of first Spanish contact, although the evidence is indirect….

“Parallel cousin marriage [like fbd marriage – h.chick] was tolerated in a very few localities, but was nowhere a preferred form.“

complicating matters though:

“POLYGAMY…

“The vast majority of North American peoples practiced polygyny. It was probably most frequent in the northern part of the Plains and Prairie areas…. Actual figures obtained from the records of priests among the Crees and Ojibwas indicate an incidence of polygyny in former times well over 20 per cent. Another area of common occurrence was the Northwest Coast. Although polygyny was limited to the wealthier class in this area, mainly because of the great amount of the bride price, it seems to have exceeded 20 per cent in many localities.

“Exclusive monogamy was the rule among the Iroquois and a few of their neighbors. This is to be expected in cultures in which matrilineal descent and matrilocal residence were coupled with female ownership and control of agricultural land and houses, not to mention the unusual authority of women in political affairs. Here the men literally moved in with their wives, who could divorce them merely by tossing their personal effects out of the door of the longhouse….”

ruh-roh! (~_^)

“The only other area where female dominance approached this level was that of the western Pueblos in the Southwest. Here the picture was similar, and exclusive monogamy prevailed. The other instances of exclusive monogamy were scattered and occurred in both bilateral and patrilineal societies. They do not lend themselves to any ready explanation.

“Sororal polygyny — that is, the marriage of a man to two wives who were sisters — probably occurred wherever polygyny was to be found. A number of Plains tribes had no other form. A man in this society was especially anxious to acquire an eldest sister as a first mate, with an eye on acquiring her younger sister if and when he could afford them…. [I]t is easy to see that polygyny had more utility in societies where male mortality in hunting and warfare was high. The Plains was one of these areas. Among the Eskimos, where a man had more difficulty in supporting multiple wives, the extremely high male mortality was offset by female infanticide. This partially explains the more modest amount of polygyny present in the Arctic.”

the turkana mating patterns are interesting, i think, for a handful of reasons:

– they appear to uphold the notion that flatlanders tend to be outbreeders (see also here) — while mountaineers/peoples in marginal lands tend to be inbreeders;
– they also appear to uphold the notion that the greater the outbreeding, the looser the family and social structures (see…half of the blog);
– and they appear to contradict the notion that pastoralists tend to inbreed (see explanations from anthropologists the world over). hmmmm.

from the paper, the turkana live here in kenya:

and this region of kenya is fairly flat:

the turkana who practice pastoralism (most of them — a few are agriculturalists) apparently do bring their herds (of camels and goats) uphill for grazing in the summer, but mostly they reside in the valleys, and they consider themselves to be flatlanders rather than mountaineers.

from the paper, we learn that the turkana have clans (28 patrilineal clans) [pg. 472], that they avoid marrying within those clans — in the study, 96% of those surveyed were married to someone from another clan [pg. 474], and that they even try to avoid marrying anyone closer than second cousins [pg. 472].

(one thing that the turkana do have which complicates the picture is polygamy. clearly polygamy, like cousin marriage, also results in closer relatedness [a lot of individuals in the population are half-siblings]. i haven’t thought through polygamy yet — what it means for relatedness. obviously it depends on if only a certain portion of the males get to mate and the remainder are left out or if the whole system is more of a rotating system of polygamy and women are swapped between most or all of the men. polygamy is complicated. i’ll have to think about it one of these days.)

so, what is turkana society like? what are their family types like? what about these clans then?

“The nuclear family is the basic social and political unit among the Turkana.”

uh…kinda.

“The family comprises a man, his wife or wives, his sons and their wives and children, and his unmarried daughters. In the homestead there might also be a grandparent or other relative and a concubine (a woman living in the household to whom he is not married).

“The man is the head of the family. The family is represented economically by its herd of livestock….

“The Extended Family

“Among the Turkana, the extended family (*ngi-tungakothi*) is made up of all males who can claim common descent on the male side. The unit could go back three or four generations. To members of the group, those within it are ‘our people.’ But strictly speaking, the extended family also includes the wives of each of these men if they have raised a child to walking stage. It excludes women who have married elsewhere and are no longer in the family.

“The core of the extended family, however, is essentially the son of a deceased father, his full brothers, his half-brothers, and his paternal male first cousins, along with the nuclear families of all these men…. Members also share fellowship on other such occasions as initiation, weddings, and judicial compensation, when there is mutual assistance in givings and receiving livestock.”

“judicial compensation” there is interesting. is that like wergeld? dunno. will have to find out more.

“The Clan

“Every Turkana belongs to a clan (*ateger*), of which there are about 20. They fall into two major types: the large, widespread clans, each comprising over 1,000 adult males, and the very small ones consisting of only about 30 members.

“Clans are of little practical or political importance to the Turkana today, especially since clans no longer own herds or pastures or watering places…. Nor do travelling Turkana any longer expect help or hospitality from fellow clansmen. They would expect that help from bond-friends, people in various parts of the country to whom they have made a ritual commitment.“

“Dyson-Hudson and McCabe (1985: 79-80) describe the degree to which Turkana groups form out of myriad individual decisions:

“‘Kinship, both agnatic and affinal, is an important basis for cooperative relationships. However since livestock are a readily partible resource, and since the frequent moves of camps and splitting of the major *awi* into satellite camps allow the breaking of old bonds and the establishment of new ones, a man has great latitude to choose to live with people he likes. A woman also has some choice: she can live with her father, her brother, or her grown sons, as well as with her husband. Flux and flexibility characterize [their] social networks.‘

“Although the Turkana lack highly structured kin groups, territories, and a formal political system, they do establish and maintain large networks that amount to a kind of effective community for each homestead. First, hamletlike groups of close relatives and friends live and move together for part of the year. Second, such groups cluster within convenient walking distance of one another, and men in such a cluster meet often to take turns distributing freshly slaughtered meat and to share information on herds and pastures. These two levels of social organization (Gulliver calls them primary and secondary neighborhoods) provide the individual househead with a network of friends through which food and information flow, friends from whom he may beg insistently as a good Turkana should (Gulliver 1951; Patton 1982) and who will cooperate with him in defense against raiding. Although a family is free to move at will, in practice families tend to move with their neighbors and settle near them at new locations….

“The main cement of Turkana social organization, however, is the exchange of livestock. A nuclear family’s herds are all owned and managed by the father; and although their daily care falls to women and boys, spread over the countryside, there is a strong sense of the essential unity of the family and its herd. Some hamlet groups are the remnants of old extended families whose senior male has died: in such cases the brothers and in-laws continue to live near each other, and, because their herd once had a common owner, the men continue to feel part of one family. Often, as we have seen, the hamlet-size group also includes friends….

“How extensive is Turkana social structure? On the one hand, there are indicators of ‘tribal’ integration. The Turkana say, ‘We are all brothers,’ and respect this tribal identity by rarely raiding or using spears against one another (bandits, *igorokos*, are exceptions). They know and acknowledge the ‘territorial’ names of their regions. They also belong to clans, some of them small and localized, others widespread throughout Turkana land. In past times, apparently, whole regions of Turkana mustered thousands of warriors against non-Turkana enemies.

“Yet in their daily life the Turkana are not conscious of themselves as a tribe. They have no tribal, territorial, or clan leaders, no corporate groups, and no genealogical reckoning beyond the grandparent level. They are highly individualistic and tend to migrate within circumscribed areas; even close-knit extended families usually separate at times in response to their individual needs….“

“There would appear to be no clan leadership or organisation. Gulliver states that ‘if one asks a Turkana who is head of his clan he usually replies *there is no head, we have no heads. They were all long ago.* However a few will give the name of a man of a clan recently alive, or an old man, who achieved fame and importance for some reason and say that he is the head. But enquiry shows that he has no authority over any of them outside his own extended family should he still be alive…’ (1951: 69).”

so, the turkana outbreed, and they have loose family and social structures. friends seem to be important (as important as family?). the turkana are individualistic, yet share readily with their friends.

they do go to battle, though. mostly with non-turkana peoples. sometimes the non-turkana steal the turkana’s animals, oftentimes it’s the other way around [from here]:

“Warfare is traditionally an essential part of Turkana life and the principal occupation of young men. Weapons are considered a man’s proud possessions and the practical tool for increasing herds by raiding and for expanding their territory. Ever since they entered Kenya, the Turkana have been in a perpetual process of expansion. Previously settled tribes such as the Samburu, Pokot, Donyiro, Toposa and Karamojong were forced out of their territory by belligerent Turkana warriors (Gulliver, 1951: 143). No administration has ever able completely to contain the Turkana and put an end to these conflicts. These common age-old pursuits still trouble independent Kenya.

“Turkana believe that all livestock on earth, including that owned by other people, is theirs by right, and that there is nothing wrong in going after it and taking it by force. A young man, they say, must be prepared to die in pursuit of stock (Soper, 1985: 106).”

i love how people justify their own actions to themselves. (~_^) don’t mess with the turkana, though! they have wrist knives. yikes!: